Phonograph



I I I NOV- 3; 1919. I

. 1,399,917, Patented Dec. 13, 1921.

EVELYN J. RUIPERT ATKINSON, OF MELBOURNE, V

BIA, AUSTRALIA.

PHONOGRAIPH.

Specification of Letters Patent.

Patented Dec. 13, 1921.

Application filed November 3, 1919. Serial No. 335,339.

T 0 all whom it may concern:

Be it known that I, EVELYN J. RUPERT ATKINSON, a subject of resident ofMelbourne, in the State of Victoria, Australia,.have inventedcertain'new and useful Improvements in Phonographs,

of which the following is a specification.

The invention relates to phonographs, and particularly to phonographsadapted to reproduce sound from disk records.

An object of the invention is to produce a longer record on a givensized disk than is at present obtained.

Another object of the invention is to improve the tone of the reproducedsound by causing the undulations or waves corresponding to a given noteto be of the same length at all parts of the record groove.

Another object of the invention is to provide a disk record in which theundulations corresponding to a given note are of the same length at allparts of the record groove. Disk phonograph records consist of a diskhaving a spiral or radially progressinggroove therein, in which theundulations representing the sound waves are formed. The undulations maybe vertical and formed in the bottom of the groove or may be lateral andformed in the sides of the groove. Since the groove progresses radially,and occupies the larger portion of the area of the disk, the outerportion of the spiral groove is much longer than the inner portion ofthe spiral groove. When the disk is rotated at constant angularvelocity, as is the usual procedure, the lineal velocity of the outerportion of the groove is much greater than the linealvelocity of theinner portion of the groove. For instance, in a ten-inch record, thediameter of the outer'circle of the spiral groove is about nine inchesand its length about twenty-eight inches, whereas the diameter of theinner circle is about four inches and its length about twelve inches.Since the disk rotates at constant angular velocity, both in recordingand reproducing, it follows that at the beginning of the record thegroove moves at the rate of 28 inches per revolution, under the stylus,and at the end of'the record at the rate of 12 inches per revolution,under the stylus, so that the lineal speed of the groove with respect tothe stylus is constantly varied during the recording or reproduction ofthe record. This causes the-undulations or waves'in the outer part ofthe groove to be much longer thin-necessary and conse- (arreat Britain,and a the disk, both irfrje at a constantly quently a much longer groovethan necessary is required to reproduce a given selection. V hen theundulations are longer than necessary, a hissing soundi'sjproduced, asthe stylus moves over the recdrd, thereby interferng with the tone ofreproduction. n accordancewitlij'my invention, I rotate ""ding andreproduction, g angular velocity, so that the speed of the groove underthe stylus is constant, thereby producing undulations (for a given note)of the same length or spacing at all parts of the groove.

The invention. possesses other advantageous features, some of which,with the fore going, will be set forth at length in the followingdescription, where I shall outline in full, that form of myinventionwhich I have selected for'illustration in the drawingsaccompanying and forming part of the pt esent specification. In saiddrawings I have shown one specific embodiment of my invention, butit isto be understoodthat-I do not limit myself to such form, since theinvention, as expressed in the claims, may be embodied in a plurality offorms. In the drawings I have shown the invention as applied to a soundreproducing apparatus, but it is to be understood that it may be appliedin the same manner to a recording apparatus.

Referring to said drawings: ,5,

Figure 1 is a side elevation oii' 'a portion of a phonograph showing oneform of my invention applied thereto.

Fig.2 is an underneath view of the record table, showing the drivingmechanism.

Fig. 3 is a planner top v ew-of the record I ducing machine comprislng arotating table or disk record support record 2 rests. Engaging of therecord is a stylus sound box 6, which is supported on the angularlymovable tone arm- 7, The needle enan undulation or wave' 4, upon whichthe j in the groove 3 5, secured to the gages in the groove and travelssubstantially radially across the face of the record as it' follows theprogressionof the groove. The lower face 8 of the table 4 is smooth andarranged below said table and parallel, or substantially parallel, tothe radius thereof, is a shaft 9 which is rotated at constant speed byany suitable phonograph motor.

The shaft is suitably supported in bearings secured to the base 12arranged below the table. The shaft9 is approximately parallellongitudinally thereof, is a wheel or roller 16, having a frictionsurface, such as rubber, which is in frictional contact with the smoothunder surface of the record table The undersurface of the table may becovered with a sheet of rubber, when desired, to increase the frictionalcontact, but a smooth, metallic surface may be employed to advantage.The table bears with slight pressure against the wheel 16, so that thereis a minimum of slippage between the wheel and the disk.

Means are provided for moving the wheel 16 radially of the disk in timeand coincident with the radial progression'of the stylus acting in thegroove, so that the radial displacement of the Wheel and stylus arealways the same. Preferably, the wheel lies directly under orsubstantially directly under v the stylus. Connected "to or secured tothe tone arm 7, so that it moves angularly simultaneously and equallytherewith, is an arm 17, concentric with the'center of rotation of thetone arm.- The arm 17 is provided at its outer end with a forked end 18which embraces the wheel 16, causing it to move longitudinally on theshaft 9 coincidently with the radial movement of the stylus. As thewheel rotates at constant speed and moves radially in contact with thetable in time with the radial movement of the stylus, the lineal speedof the groove under the stylus is constant at all parts'of the-groove.This produces a uniform action on the stylus at all parts of the groove,producing uniformity of tone and permits the recording of a longerselection on a given-sized disk record than was heretofore possible withdisk records rotating at constantangular velocity.

I claim:

1. In a phonograph for reproducing from disk records, a rotatablesupport for the rec- 0rd, a rotatable shaft arranged parallel to thesurface of said support and disposed radially with respect to saidsupport, a

wheel engaging said surface and splined to said shaft, means forrotating said shaft, and means controlled by a record on said supportfor moving said wheel longitudinally of said shaft.

2; In a phonograph for reproducing from disk records, a rotatablesupport for the rocord,'a rotatable shaft arranged parallel to and belowthe surface of said support'and disposed radially with respect to'theaxis of rotation of the support, a wheel slidably and nonrotatively'mounted on said shaft, means for rotating the shaft, and a lever securedto the tone arm of the phonograph to extend radially. therefrom andhaving a forked end embracing the sliding wheel so as to shiftthesamealong its shaft under the control of the swinging movement of the tonearm. I

In testimony whereof I have hereunto set my hand at asadena, California,this 24th day of October, 1919.

I EVELYN J. RUPERT ATKINSON]

